JP2976945B2 - Image drawing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image drawing device capable of performing three-dimensional drawing on a display screen of a display device.

[0002]

2. Description of the Related Art FIG. 12 is a block diagram showing a configuration example of a conventional image drawing apparatus. The image drawing apparatus includes a CRT 10 for displaying an image, a frame buffer 12 for storing display data corresponding to a display screen of the CRT 10, and a two-dimensional drawing circuit for drawing a desired rectangular image on the frame buffer 12. 14, a Z buffer 16 for storing depth data (Z value) for performing three-dimensional rendering on the frame buffer 12, and a three-dimensional rendering on the frame buffer 12 based on the depth data stored on the Z buffer 16. A three-dimensional line drawing circuit 18 and a Z buffer 16
A Z-buffer setting circuit 20 for setting data of a desired rectangular area, a processor 22 for performing overall control of the image drawing apparatus, and a main memory 24 for providing a control program and a work area for the processor 22. Having. In the above configuration, first, the processor 22
Creates two-dimensional drawing data on the main memory 24. The two-dimensional drawing data is formed, for example, as a set of line segments (straight lines). By writing this into the frame buffer 12, an image is displayed on the CRT 10.

The two-dimensional drawing circuit 14 is a circuit dedicated to writing a specific two-dimensional image into the frame buffer 12 at high speed, and specifically, a dedicated circuit for drawing a two-dimensional straight line, and a two-dimensional rectangular area is painted. There are a dedicated circuit, a dedicated circuit for transferring a dimensional rectangular area to another position, and the like. The two-dimensional drawing circuit 14 sets the address and the like for specifying the shape and the position of the two-dimensional image as described above, and sets the color data and the like to be drawn so that the attribute of the two-dimensional image to be drawn is High-speed drawing is realized by a corresponding regular coordinate calculation operation.

Next, three-dimensional drawing is performed using the Z buffer 16 and the three-dimensional straight line drawing circuit 18. The Z buffer 16 stores depth data (Z value) of each pixel (XY coordinate) drawn in the frame buffer 12. 3D straight line drawing circuit 1
8 is a three-dimensional straight line XY input from the processor 22.
Depth data (source Z value) of each point in coordinates, and Z
This processing compares the depth data (destination Z value) stored in the buffer 16 in advance, selects the data having the smaller depth, and rewrites the data in the frame buffer 12. Thus, when a three-dimensional object is drawn as a two-dimensional image, a natural image can be drawn in which a back object is hidden by a front object.

FIG. 13 is a block diagram showing a configuration of the three-dimensional straight line drawing circuit 18. As shown in FIG. This three-dimensional straight line drawing circuit 18
A register 102 for storing a source Z value input from the processor 22, a comparator 104 for comparing the source Z value stored in the register 102 with a destination Z value stored in the Z buffer 16, A ROP (Raster Operation Processor) circuit for performing a logical operation on a source value and data originally present on the frame buffer 12 by a logical circuit such as AND, OR, XOR or the like at the time of drawing, and reflecting the result on the drawing data 10
6, a straight line operation circuit 108 for drawing a straight line on the frame buffer 12 by giving coordinate parameters of a start point and an end point of a straight line to be drawn, and a transfer circuit 110 for rewriting the Z buffer 16 based on the operation result of the comparator 104
And a frame buffer address operation unit 1 for generating and controlling an address for accessing the frame buffer 12
12 and a Z-buffer address operation unit 114 for generating and controlling an address for accessing the Z-buffer 16.

FIG. 14 is an explanatory diagram for explaining the calculation process of the Z value when an arbitrary vector (straight line) is drawn. When a straight line is drawn from the coordinates (Xs, Ys) to the coordinates (Xe, Ye), the coordinates and the Z value are calculated for each pixel constituting the straight line. The calculation of the Z value is based on the value (Zs = initial value) at the start point coordinates (Xs, Ys) and the increment (Zi) between each pixel, which are provided by the processor 22. (Xe, Ye). Then, the Z value calculated in this manner is compared with the Z value of the pixel originally existing at the coordinates by the comparator 104. If the newly calculated Z value is small, the calculation result is written to the Z buffer 16, Also, writing of pixels to the frame buffer 12 is permitted, and pixels by new drawing are written. If the newly calculated Z value is large, both the Z buffer 16 and the frame memory 12 are left as they are (that is, the original pixel remains). Note that there is a system in which such control is performed by software instead of being performed by hardware as the three-dimensional straight line drawing circuit 18.

In such an image drawing apparatus,
A method for setting the value of the Z buffer 16 is as follows. A method in which the Z buffer 16 is directly accessed by the processor 22 and an address for setting the Z value is calculated by the processor 22 so that the Z values are set one by one. A method of setting a Z value in the Z buffer 16 using the three-dimensional line drawing circuit 18 as described above. A method of setting a Z value using the Z buffer setting circuit 20. Among them, in the method of directly setting the Z value by the processor 22, the Z value is set one by one at each point of the set area.
Therefore, high-speed processing is difficult and the load on the processor 22 that controls the entire system increases.

In the method of setting the Z value in the Z buffer 16 by using the three-dimensional straight line drawing circuit 18, each line segment forming the scan line of the area to be set is set to the above-mentioned start point and end point. By designating and drawing one by one, a desired area can be set. Particularly, for a graphic having a relatively simple shape, the processor 22 described above is used.
The processing can be performed at a higher speed as compared with the method of directly setting by using However, this method performs a drawing process by specifying a large number of line segments, and includes a process of comparing the Z values of each point. Therefore, the method is slower than the method using the Z buffer setting circuit 20. It is.

Next, using the Z buffer setting circuit 20, Z
As a method of setting the value, it is possible to set the Z value even faster than in the three-dimensional straight line drawing circuit 18. That is, the Z buffer setting circuit 20 stores the specific two-dimensional image in the Z buffer 1
6 is a circuit dedicated to high-speed writing into the Z buffer 16
By designating the two-dimensional area within the area and specifying the Z value to be set, high-speed setting is realized by a regular coordinate calculation operation according to the attribute of the two-dimensional area for setting the Z value. Further, by such a Z buffer setting circuit 20, an operation of transferring a specific area in the Z buffer 16 to another area can be performed at a high speed.

[0010]

However, in the above-described conventional image drawing apparatus, a dedicated Z-buffer setting circuit 20 must be provided in order to perform high-speed setting and transfer to the Z-buffer 16, which is expensive. There is a configuration problem. The two-dimensional drawing circuit 14 and the Z-buffer setting circuit 20 described above have a similar configuration in a portion for performing a coordinate calculation of a specific area. However, the frame buffer 12 and the Z-buffer 16 to be accessed are respectively. , It is difficult to divert each other. This is due to the difference in the number of bytes per pixel between the frame buffer 12 and the Z buffer 16. That is, the number of bytes per pixel in the frame buffer 12 is determined according to the gradient of the color data stored in the frame buffer 12,
For example, when each color component has a gradient of 255, one byte of data is required for each pixel for each color component, and the number of bytes per pixel is 4 bytes (32 bits) for four color components. Become. On the other hand, the Z buffer 16
The number of bytes per pixel in is determined by the depth resolution based on the Z value data. If the number of bytes per pixel is increased, a complicated stereoscopic image can be drawn in the depth direction. For example, two-byte Z value data per pixel is used. The gradient of the color data stored in the frame buffer 12 and the resolution of the Z value data stored in the Z buffer 16 are usually different from each other. Is also different.

Therefore, as shown in FIG. 12, the two-dimensional drawing circuit 14 for the frame buffer 12 and the Z-buffer setting for the Z-buffer 16 must be set in order to process the buffers 12 and 16 at high speed. It is necessary to provide the circuit 20 and the circuit 20 individually, which is an obstacle to cost reduction. In addition, in an apparatus using the Z buffer 16 as described above, a high-speed system configuration is often used even if the price is high. The bus interface with the three-dimensional linear drawing circuit 18 and the like is also provided separately.
It is difficult to use the circuit 4 and the Z buffer setting circuit 20 at the same time. As a result, it is difficult to reduce the cost. SUMMARY OF THE INVENTION It is an object of the present invention to provide an image drawing apparatus in which a two-dimensional drawing circuit for a frame buffer can be used as a setting circuit for a Z buffer, and both high-speed setting processing of the Z buffer and cost reduction can be achieved. is there.

[0012]

According to the present invention, there is provided a frame buffer for storing display data corresponding to a display screen of a display device, and a specific two-dimensional image is drawn on the frame buffer. A two-dimensional drawing circuit that performs coordinate calculation of: a Z buffer that stores depth data for performing three-dimensional drawing with respect to the frame buffer; and a tertiary image that is stored in the frame buffer based on the depth data stored in the Z buffer. An image drawing apparatus having a three-dimensional line drawing circuit for performing original drawing, a memory control circuit for setting each area of the frame buffer and the Z buffer on the same physical memory, and controlling access to each buffer; The number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit is related to the drawing data of the frame buffer. Means for changing the number of bits to be performed or the number of bits corresponding to the depth data of the Z buffer, wherein the number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit is changed by the number of bits changing means. Thereby, the drawing in the frame buffer and the setting of the depth data in the Z buffer are selectively performed by the coordinate calculation of the two-dimensional drawing circuit.

In the image drawing apparatus of the present invention, the memory control circuit appropriately sets each area of the frame buffer and the Z buffer on the same physical memory, and selectively accesses two buffer areas from the two-dimensional drawing circuit. When accessing the frame buffer from the two-dimensional drawing circuit, the number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit is changed to the number of bits corresponding to the drawing data of the frame buffer by the bit number changing means. to access. When the two-dimensional drawing circuit accesses the Z buffer, the number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit is changed to the number of bits corresponding to the depth data of the Z buffer by the bit number changing means. to access. Thereby, the drawing and transfer of the specific image to the frame buffer and the setting and transfer of the specific area to the Z buffer can be performed at high speed by the common two-dimensional drawing circuit. Further, by making the Z buffer have the same configuration as the frame buffer by the memory control circuit, two frame buffers having the same size as the number of bits per pixel are set on the physical memory, By alternately performing drawing in each frame buffer without changing the number, a system in which each frame buffer is used as a double buffer for animation can be constructed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image drawing apparatus according to the present invention will be described below. FIG. 1 is a block diagram illustrating a configuration of an image drawing apparatus according to a first embodiment of the present invention. This image drawing device is a CRT 2 for displaying images.
10 and a frame buffer 22 for display on the CRT 210
A buffer memory 240 having a Z buffer 230 for zero and three-dimensional drawing, and a two-dimensional drawing circuit 200 for drawing and setting a desired rectangular area in the buffer memory 240
A memory control circuit 250 for controlling the setting and access of each buffer area to the buffer memory 240; and a three-dimensional linear drawing circuit 260 for performing three-dimensional drawing in the frame buffer 220 based on the Z value data stored in the Z buffer 230. And a main memory 280 that provides a control program and a work area for the processor 270 to control the entire image drawing apparatus. The three-dimensional line drawing circuit 260 draws a three-dimensional line in the frame buffer 220 based on the principle shown in FIG. 14 similarly to the three-dimensional line drawing circuit 18 shown in FIG. The above-mentioned source Z value is supplied to the straight line drawing circuit 260. 3D straight line drawing circuit 2
The 60 compares the source Z value from the processor 270 with the destination Z value stored in the Z buffer 230, and draws a three-dimensional straight line in the frame buffer 220 based on the comparison result.

In the image drawing apparatus of this embodiment, the frame buffer 2 is stored in the buffer memory 240 which is the same physical memory.
20 and a Z buffer 230, and a memory control circuit 250
As a result, the two-dimensional drawing circuit 200
0 and 230 can be freely accessed. Note that, in this example, the frame buffer 220
It has a size of 640 × 480 pixels (pixels) and stores 8-bit, 16-bit or 32-bit color data per pixel. As described above, the number of bits per pixel in the frame buffer 220 is determined by the gradation of the color data. The gradation of the color data is determined by a keyboard (not shown) by an operator.
Is determined by an input from an application or the like or application software. It is also assumed that the start address of the frame buffer 220 is 300000h. Note that the h at the end indicates that it is a hexadecimal number.

The Z buffer 230 is 640 × 48
It has a size of 0 pixels, and the depth is represented by a Z value of 16 bits or 32 bits per pixel. As described above, the number of bits per pixel in the Z buffer 230 is determined by the depth resolution based on the Z value data. Further, the depth resolution based on the Z value data is determined by an input from a keyboard or the like by an operator or application software. The head address of the Z buffer 230 is 3004B0
0h. Further, the two-dimensional drawing circuit 200 in the present example is configured as a dedicated circuit for performing a filling process of a rectangular area. And the frame buffer 2
For 20, a process of painting a desired rectangular area with a desired color is performed. The Z value is set in a desired rectangular area for the Z buffer 230, and processing such as initial setting is performed.

FIG. 2 is a block diagram showing the configuration of the two-dimensional drawing circuit 200. As illustrated, the two-dimensional drawing circuit 200 includes a register unit 300 for setting various parameters for performing a filling process of a rectangular area, and a frame buffer 220 and a Z buffer based on the parameters set in the register unit 300. A memory address operation unit 330 that performs an address operation on the buffer 230. The register unit 300 includes a drawing pixel byte number setting register 302 and a drawing head address setting register 3.
04, a start point setting register 306, a width / height register 308, a drawing mode setting register 310, a start setting register 312, and a color setting register 314.
The setting of each parameter in the register unit 300 is performed by the frame buffer 22 based on an input from a keyboard or the like by an operator or application software.
Prior to accessing the 0 or Z buffer 230, it is performed by the processor 270. Processor 270 includes:
When drawing a rectangle in the frame buffer 220 and the Z buffer 2
At the time of drawing a rectangle on the H.30 (when setting Z data), settings are made by changing the drawing start address and the drawing pixel byte number. The two-dimensional drawing circuit 200 calculates the address of the drawing pixel in the rectangular area in the memory address calculation unit 330 based on the setting of each parameter in the register unit 300 as described above, and stores this address in the memory control circuit 25.
Output to 0. The memory control circuit 250 accesses the frame buffer 220 or the Z buffer 230 based on the address from the memory address operation unit 330, and writes the color data or the Z value data stored in the color setting register 314. At this time, the frame buffer 220 is accessed based on the drawing start address set in the drawing start address setting register 304, or Z
It is determined whether to access the buffer 230. Also,
When accessing the frame buffer 220 based on the number of bytes set in the drawing pixel byte number setting register 302, data is written in the number of bytes corresponding to the frame buffer 220, and the Z buffer 23
When accessing 0, data is written in the number of bytes corresponding to the Z buffer 230. Also, a start point setting register 306, a width / height register 308, a drawing mode setting register 310, and a start setting register 3
The function of each parameter set in the buffer 12 is to access the frame buffer 220 or to the Z buffer 2.
This is common to the case where the user accesses the 30. The address calculation in the memory address calculation unit 330 is performed in synchronization with the data writing operation in the memory control circuit 250 based on, for example, a synchronization signal from the memory control circuit 250. Hereinafter, the details of the two-dimensional drawing circuit 200 will be described.

FIG. 3 is an explanatory diagram showing a specific example of a relationship between a memory address and a format for each setting register of the register section 300 in the present embodiment. It is assumed that the register section 300 of this example has a width of 32 bits, and the start address of the register section 300 is 200000h. The drawing pixel byte number setting register 302 constitutes a bit number changing unit, and corresponds to the buffer 220 or 230 to be accessed, and calculates the number of bits per pixel when calculating a rectangular address in byte units. This is a register set by 0. If the number of bits per pixel is 8, 0h, 16 if 1h, 32 if 2
Set h.

Drawing start address setting register 304
Is the origin (0,0) of the coordinate system that specifies the rectangle to be drawn, corresponding to the buffer 220 or 230 to be accessed.
Is set. The start point setting register 306 is a register for setting the pixel coordinates of the upper left point of the rectangle to be filled, and the upper 16 bits represent the Y coordinate and the lower 16 bits represent the X coordinate. The width / height register 308 stores the width / width of the rectangle to be filled.
Data indicating the height is set. The upper 16 bits indicate the height, and the lower 16 bits indicate the width. In this example, the upper left point of the rectangle and the width of the rectangle
Although the rectangle is designated by the height, the rectangle may be designated by the upper left point and the lower right point of the rectangle instead.

The drawing mode setting register 310 is a register for selecting a straight line drawing or a rectangular drawing, and sets 1h when painting a rectangle. Start setting register 31
Reference numeral 2 denotes a register for instructing start of drawing, and drawing is activated by setting 1 to this register 312. The color setting register 314 is a register for setting a color for painting a rectangle or a Z value of the rectangle.
If it is a bit (1 byte), set color data by 8 bits. If it is 16 bits (2 bytes), set color data or Z value by 16 bits, and set 32 bits (4 bytes).
Then, color data or Z value by 32 bits is set. When clearing the Z buffer 230, 0h is set in the color setting register 314, and 0 clear data is written to each point. In the three-dimensional drawing using the Z buffer 230, it is often necessary to clear the Z buffer 230. By writing a rectangle into the Z buffer 230 by the two-dimensional drawing circuit 200 as described above, the Z buffer 230 can be cleared. Can be done at high speed. Since this clearing requires a large amount of memory access, the two-dimensional drawing circuit 20
By using 0, the processing can be speeded up.

FIG. 4A shows the Z buffer 230 based on rectangular data of 0h corresponding to the entire area of the Z buffer 230.
This shows a state in which the whole is cleared to zero. On the other hand, FIG.
As shown in (B), the window displayed on the screen of the CRT 210 can be cleared to zero. If the number of data bits (the number of bytes) per pixel is different between the frame buffer 220 and the Z buffer 230,
The calculation formula for calculating the physical address from the starting point / width / height information of the rectangle must be changed. However, by providing the drawing pixel byte number setting register 302, the frame buffer 220 can be painted over on the frame buffer 220.
A rectangle can be designated by the coordinate designation method (x, y) of No. 20 and the rectangle can be designated by the coordinate system (x, y) on the Z buffer 230 in the filling on the Z buffer 230. That is, by using this register 302, the frame buffer 2
A common two-dimensional drawing circuit 200 can be used even if the number of pixels of the Z buffer 230 differs from that of the Z buffer 230. In addition, the memory address calculation unit 330, based on the setting parameters of the register unit 300 as described above,
The address of each point of each pixel to be drawn is calculated.

FIG. 5 is an explanatory diagram showing a setting example of the color setting register 314 for the same rectangle of the frame buffer 220 and the Z buffer 230. FIG. 5A shows an example of drawing data for the frame buffer 220. The color setting register 314 specifies "AL
Data of PHA, “RED”, “GREEN”, and “BLUE” are set. FIG. 5B shows the Z buffer 2.
The example of the Z value with respect to 30 is shown, and “Z” is set as the Z value data. Also, start point setting register 3
06 and the width / height register 308 are set to the same value.

FIG. 6 shows a state in which a rectangular area is filled in the frame buffer 220 by setting the register shown in FIG. 5A, and a Z value is stored in the rectangular area of the Z buffer 230 by setting the register shown in FIG. Is set. 6, register 1 is a drawing start address setting register 304, register 2 is a drawing pixel byte number setting register 302, register 3 is a starting point setting register 306, and register 4 is a width / height register 30.
8, register 5. is a color setting register 314. In addition,
The two-dimensional drawing circuit 200 usually includes the frame buffer 22
The display data is stored in a state of storing by 0,
Only when the setting to the Z buffer 230 is performed, the data is temporarily rewritten to the data for setting the Z buffer 230, and after the setting to the Z buffer 230 is completed, the data is automatically rewritten to the data for the frame buffer 220. To For example, when the Z buffer 230 has 32 bits per pixel and the frame buffer 220 has other than 32 bits per pixel, the drawing pixel byte number setting register 302 of the two-dimensional drawing circuit 200 is temporarily set to 32 bits. After setting the Z buffer 230,
The drawing pixel byte number setting register 302 is changed to a value suitable for the frame buffer 220.

Next, a procedure for clearing the entire area of the Z buffer 230 in this embodiment will be described. FIG.
Is a flowchart showing an operation procedure when the Z buffer 230 is cleared. First, from the processor 270,
The setting of the register unit 300 is performed. At first, the drawing mode setting register 310 specifies the rectangle filling mode 1
h is set (step S2). Next, 3004B00h is set in the drawing start address setting register 304 (step S4). Next, 32 bpp = 2h is set in the drawing pixel byte number setting register 302 (step S6). Note that bpp indicates the number of bits per pixel (bitper pixel). Next, (0, 0) = 0h is set in the start point setting register 306 (step S8). Next, (width 640, height 480) is set in the width / height register 308 (step S1).
0). That is, here, the entire area of the Z buffer 230 is designated in order to clear the entire area of the Z buffer 230. Further, the color setting register 314 is set to 0h (Z value =
0) (step S12). Then, by setting 1h in the start setting register 312 (step S14), the clearing process is started.

First, when the clearing process is started, the address of the drawing point is calculated by the memory address calculation unit 330 of the two-dimensional drawing circuit 200 from the following formula, and the memory control circuit 2
50 (step S16). Drawing point address = head address + X coordinate × number of pixel bytes for drawing + Y coordinate × number of pixel bytes for drawing × number of pixels of one scan line The memory control circuit 250 sends a color on the address sent from the two-dimensional drawing circuit 200. The value of the setting register 314 is written (Step S18). When one writing operation is completed, the memory address calculation unit 330 of the two-dimensional drawing circuit 200 calculates the next drawing point (step S1).
6) With reference to the drawing pixel byte number, the address is advanced by one pixel byte number, and the value of the color setting register 314 is written on the next drawing point (step S1).
8). When drawing is performed to the right end of the rectangular area, the address is advanced by (the number of scan line bytes−the number of rectangular bytes), and the value of the drawing point on the next scan line is written. It is determined whether the above operation has been performed for all the pixels in the rectangular area (step S20).
If not, the process returns to step S16 and returns to step S1.
6. The processing of S18 is executed. As described above, in the image drawing apparatus of the present example, the Z buffer 230 can be cleared or rewritten using the two-dimensional drawing circuit 200 for the frame buffer 220, and the Z buffer
A high-speed setting of 0 can be realized.

Next, a second embodiment of the present invention will be described. In the example described above, the case where a rectangular filling circuit is adopted as the two-dimensional drawing circuit 200 has been described.
In this example, a case where a rectangular transfer circuit is employed as the similar two-dimensional drawing circuit 200 will be described. In a window-type OS (Operating System), application windows frequently move. For this reason, in a system using a Z buffer, it is necessary to move not only data on the frame buffer but also data on the Z buffer corresponding to the rectangle of the window. FIG. 8 shows a state in which the drawing data in the frame buffer 220 and the Z value data in the Z buffer 230 move as the window moves on the CRT screen. In this figure, (A) shows the case where the left and right three-dimensional application windows on the CRT screen have moved to the lower right, and (B) shows the case where the color value data of the rectangular area has moved on the frame buffer 220. (C) shows the case where the Z value data of the rectangular area has moved on the Z buffer 230. In this example, the two-dimensional drawing circuit 200 is used to move the rectangular data on the Z buffer at high speed.

FIG. 9 is a block diagram showing the configuration of the two-dimensional drawing circuit 200 of this embodiment. As shown, the two-dimensional drawing circuit 200 is obtained by changing a part of the register section 300 in the configuration shown in FIG. That is, in the two-dimensional drawing circuit 200 of the present example, a transfer source rectangle start point position setting register 320 that stores a transfer source rectangle start address,
A destination rectangular start point position register 322 for storing a destination rectangular start address of the destination. Also in this example, a drawing pixel byte number setting register 302, a drawing head address setting register 304, a width / height register 308, a drawing mode setting register 310, a start setting register 312, and a color setting register 314 are provided. These have the same function as the example shown in FIG. 2 described above.

FIG. 10 shows the register section 300 in this embodiment.
FIG. 4 is an explanatory diagram showing a specific example of a relationship between a memory address and a format for each setting register. The transfer source rectangle start position setting register 320 stores the pixel coordinates of the upper left point of the transfer source rectangular area, and stores the Y coordinate in the upper 16 bits and the X coordinate in the lower 16 bits. The transfer destination rectangle start point position register 322 stores the pixel coordinates of the upper left point of the transfer destination rectangular area.
The Y coordinate is stored in 6 bits, and the X coordinate is stored in the lower 16 bits. In this example, the transfer source rectangular position is set to (10, 7).
0), the transfer rectangle width and height are (210, 50), and the transfer destination rectangle position is (130, 200). Further, the color setting register 314 of this example stores a Z value to be set in an area after the transfer source rectangular area is cleared by transfer, and stores 0h in this example.

Next, a procedure for transferring a rectangular area of the Z buffer 230 in this embodiment will be described. FIG.
9 is a flowchart showing an operation procedure at the time of transfer of the Z buffer 230. First, the processor 270 sets the register section 300. First, 2h for designating the rectangular transfer mode is set in the drawing mode setting register 310 (step S32). Next, 3004B00h is set in the drawing start address setting register 304 (step S34). Next, 32 bpp = 2h is set in the drawing pixel byte number setting register 302 (step S36). Next, the transfer source rectangle start point position setting register 32
(10, 70) is set to 0 (step S38). Next, (13) is set in the transfer destination rectangle start point position register 322.
(0, 200) (step S40). Next, (width 210, height 50) is set in the width / height register 308 (step S42). Further, the color setting register 31
4 is set to 0h (Z value = 0) (step S44).
Then, by setting 1h in the start setting register 312 (step S46), the clearing process is started.

When the clearing process is started, first, the memory address calculating section 330 of the two-dimensional drawing circuit 200 calculates the address of the drawing point in the transfer source rectangular area from the following formula and sends it to the memory control circuit 250 (step). S4
8). Drawing point address = head address + X coordinate × number of pixel bytes for drawing + Y coordinate × number of pixel bytes for drawing × number of pixels of one scan line The memory control circuit 250 determines the Z corresponding to the address sent from the two-dimensional drawing circuit 200. The Z value of the buffer 230 is read and stored in a transfer register (not shown) (step S50). Then, the value (0h) of the color setting register 314 is written on the address (step S5).
2). Next, the address of the drawing point in the transfer destination rectangular area is calculated by the same formula as used in step S48, and is sent to the memory control circuit 250 (step S54).
The memory control circuit 250 writes the Z value stored in the transfer register on the address sent from the two-dimensional drawing circuit 200 (step S56). When one transfer is completed, the process returns to step S48 to transfer the next drawing point. The above operation is performed for all pixels in the rectangular area (step S58). As described above, in the image drawing device of the present embodiment, the frame buffer 22
0 using the two-dimensional drawing circuit 200 for the Z buffer 230
Transfer of a rectangular area of
High-speed rewriting of the buffer 230 can be realized.

Next, a third embodiment of the present invention will be described. In the image drawing apparatus of this embodiment, a double buffer system having two frame buffers is constructed by using the same size of the Z buffer 230 as the frame buffer 220 and using the same number of bits per pixel. This double-buffer system is a display system used in animation, in which one screen (frame) of an animation stored in one frame buffer is displayed while the next screen (frame) is displayed in the other frame buffer. In this system, animation is accelerated by switching each frame buffer by hardware, and the screen is prevented from being disturbed during the drawing operation. In the above-described image drawing apparatus, two frame buffers are configured on the buffer memory 240 by the function of the drawing start address setting register 304, and each frame buffer is alternately selected by the memory control circuit 250 to perform animation drawing. Do
In synchronization with this, by alternately switching each frame buffer displayed on the screen of the CRT 210, it is possible to function as a double buffer system.

By combining the function of such a double buffer system with the above-described three-dimensional image drawing function and window display system, the buffer memory 24
0 can be widely applied to various uses, and particularly useful multimedia-compatible devices can be provided. Further, in each of the above examples, a case has been described in which a two-dimensional drawing circuit that draws or transfers a two-dimensional rectangle is provided.
The present invention can be similarly applied to a case where a two-dimensional drawing circuit for drawing a two-dimensional straight line is provided.

[0033]

As described above, in the image drawing apparatus of the present invention, each area of the frame buffer and the Z buffer is set on the same physical memory, and the number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit is set. Is changed, the drawing in the frame buffer and the setting of the depth data in the Z buffer can be selectively performed by the coordinate calculation of the two-dimensional drawing circuit. As a result, the two-dimensional drawing circuit for the frame buffer can be used as the setting circuit for the Z buffer, and the setting of depth data in the Z buffer can be speeded up without providing a dedicated setting circuit for the Z buffer. , Z-buffer high-speed setting processing and cost reduction.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an image drawing apparatus according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a two-dimensional drawing circuit provided in the image drawing apparatus shown in FIG.

FIG. 3 is an explanatory diagram showing a specific example of a register unit provided in the two-dimensional drawing circuit shown in FIG. 2;

FIG. 4 is an explanatory diagram showing a manner of clearing a rectangular area of a Z buffer in the image drawing apparatus shown in FIG. 1;

5 is an explanatory diagram showing a setting example of a color setting register for the same rectangle of a frame buffer and a Z buffer in the image drawing apparatus shown in FIG. 1;

6 is an explanatory diagram showing a state in which a rectangular area is filled in a frame buffer by setting a register shown in FIG. 5, and a state in which a Z value is set in a rectangular area of a Z buffer.

FIG. 7 is a flowchart showing an operation when the Z buffer is cleared in the image drawing apparatus shown in FIG. 1;

FIG. 8 is an explanatory diagram showing a state in which the drawing data in the frame buffer and the Z value data in the Z buffer move as the window moves on the CRT screen in the window display system.

FIG. 9 is a block diagram showing a configuration of a two-dimensional drawing circuit of an image drawing device according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram showing a specific example of a register unit provided in the two-dimensional drawing circuit shown in FIG. 9;

11 is a flowchart showing a transfer operation of a rectangular area of a Z buffer in the image drawing apparatus shown in FIG. 1;

FIG. 12 is a block diagram illustrating a configuration example of a conventional image drawing apparatus.

13 is a block diagram showing a configuration of a three-dimensional straight line drawing circuit in the image drawing device shown in FIG.

FIG. 14 is an explanatory diagram illustrating a calculation process of a Z value when an arbitrary vector (straight line) is drawn using the three-dimensional straight line drawing circuit illustrated in FIG. 13;

[Explanation of symbols]

200: two-dimensional drawing circuit, 210: CRT, 220
…… Frame buffer, 230 …… Z buffer, 240
...... Buffer memory, 250 ... Memory control circuit, 26
0: three-dimensional line drawing circuit, 270: processor, 2
80: main memory, 300: register unit, 302
…… Drawing pixel byte number setting register, 304…
Drawing start address setting register, 306... Start point setting register, 308... Width / height register, 310... Drawing mode setting register, 312.
314: a color setting register, 320: a transfer source rectangular start point position setting register, 322, a transfer destination rectangular start point position register, 330: a memory address calculation unit.

Claims (10)

(57) [Claims] A frame buffer for storing display data corresponding to a display screen of a display device; a two-dimensional drawing circuit for performing a coordinate calculation for drawing a specific two-dimensional image in the frame buffer; Image drawing comprising: a Z-buffer for storing depth data for performing three-dimensional drawing on the image data; and a three-dimensional line drawing circuit for performing three-dimensional drawing in the frame buffer based on the depth data stored in the Z buffer. In the apparatus, a memory control circuit for setting each area of the frame buffer and the Z buffer on the same physical memory and controlling access to each buffer; and a number of bits per pixel in a coordinate calculation of the two-dimensional drawing circuit. Is the number of bits corresponding to the drawing data of the frame buffer or the depth data of the Z buffer. Bit number changing means for changing the number of bits corresponding to the number of bits in the frame buffer by changing the number of bits per pixel in the coordinate calculation of the two-dimensional drawing circuit by the bit number changing means. And setting of depth data in the Z buffer is selectively performed by coordinate calculation of the two-dimensional drawing circuit. 2. The image drawing apparatus according to claim 1, wherein said bit number changing means changes the number of bits per pixel in byte units. 3. The bit number changing unit sets a bit number corresponding to the frame buffer or the Z buffer in a bit number setting unit provided in the two-dimensional drawing circuit and configured to set a bit number per pixel. The image drawing apparatus according to claim 1, configured as described above. 4. The two-dimensional drawing circuit has a region setting unit for setting a drawing region of a specific figure, and stores the drawing buffer in the frame buffer or the Z buffer based on an address of a drawing region set in the region setting unit. 2. The image drawing device according to claim 1, wherein the image drawing device is selectively accessed. 5. The two-dimensional drawing circuit has a bit number setting unit for setting the number of bits per pixel, and a data setting unit for setting data to be written in the specific graphic, and draws the image on the frame buffer. Sometimes, the number of bits corresponding to the frame buffer is stored in the number of bits setting unit, and the color data is stored in the data setting unit. When the number of bits is set in the Z buffer, the number of bits is set in the Z buffer. 2. The image drawing apparatus according to claim 1, wherein a corresponding bit number is stored, and depth data is stored in the data setting unit. 6. The image drawing apparatus according to claim 1, wherein the two-dimensional drawing circuit is a circuit for drawing a two-dimensional straight line. 7. The image drawing apparatus according to claim 1, wherein the two-dimensional drawing circuit is a circuit for painting a two-dimensional rectangular area. 8. The image drawing apparatus according to claim 1, wherein the two-dimensional drawing circuit is a circuit for transferring a two-dimensional rectangular image to another position. 9. The three-dimensional straight line drawing circuit, wherein the depth data at each point on the input three-dimensional straight line,
2. The image drawing apparatus according to claim 1, wherein a process of comparing the depth data stored in the buffer in advance and selecting data having a smaller depth to rewrite the data in the frame buffer is performed. 10. Two frame buffers having the same size as the number of bits per pixel are set on the physical memory, and the number of bits for each frame buffer is changed without changing the number of bits by the bit number changing means. 2. The image drawing apparatus according to claim 1, wherein each frame buffer is used as a double buffer for animation by performing drawing alternately.